On MacOS, it would be Cmd+Shift+L instead of Ctrl+Shift+L.
But for it to work (whether in Windows or MacOS), you need to have a properly matching URL. When you are on the website’s login page, do you see a numerical badge counter in the corner of the Bitwarden icon? It would look like the following in a Windows Chrome browser, and I believe the counter is red in Safari:
The number shown (1 in the above example) indicates the number of matching login items available.
Edited to Add: Since your screenshot above is from the Reddit login form, in case you are using Safari, you should be aware that there is a bug affecting the Safari browser extension autofill on the new Reddit site specifically (see: Auto Fill is pasting password in website search box); autofilling login credentials on old Reddit should still work in Safari.